feat: Allow query distinct a range of documents

This commit is contained in:
Clément Renault 2018-12-16 14:22:04 +01:00
parent d0ee5f12a0
commit 4a310c31ab
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@ -165,42 +165,80 @@ where D: Deref<Target=DB>,
F: Fn(DocumentId, &DatabaseView<D>) -> Option<K>, F: Fn(DocumentId, &DatabaseView<D>) -> Option<K>,
K: Hash + Eq, K: Hash + Eq,
{ {
pub fn query(&self, query: &str, limit: usize) -> Vec<Document> { pub fn query(&self, query: &str, range: Range<usize>) -> Vec<Document> {
let mut documents = self.inner.query_all(query); let mut documents = self.inner.query_all(query);
let mut groups = vec![documents.as_mut_slice()]; let mut groups = vec![documents.as_mut_slice()];
let mut key_cache = HashMap::new();
let view = &self.inner.view; let view = &self.inner.view;
for criterion in self.inner.criteria.as_ref() { // these two variables informs on the current distinct map and
let tmp_groups = mem::replace(&mut groups, Vec::new()); // on the raw offset of the start of the group where the
let mut seen = DistinctMap::new(self.size); // range.start bound is located according to the distinct function
let mut distinct_map = DistinctMap::new(self.size);
let mut distinct_raw_offset = 0;
'group: for group in tmp_groups { 'criteria: for criterion in self.inner.criteria.as_ref() {
group.sort_unstable_by(|a, b| criterion.evaluate(a, b, view)); let tmp_groups = mem::replace(&mut groups, Vec::new());
for group in GroupByMut::new(group, |a, b| criterion.eq(a, b, view)) { let mut buf_distinct = BufferedDistinctMap::new(&mut distinct_map);
for document in group.iter() { let mut documents_seen = 0;
match (self.function)(document.id, view) {
Some(key) => seen.register(key), for group in tmp_groups {
None => seen.register_without_key(), // if this group does not overlap with the requested range,
}; // push it without sorting and splitting it
} if documents_seen + group.len() < distinct_raw_offset {
documents_seen += group.len();
groups.push(group); groups.push(group);
if seen.len() >= limit { break 'group } continue;
}
group.sort_unstable_by(|a, b| criterion.evaluate(a, b, view));
for group in GroupByMut::new(group, |a, b| criterion.eq(a, b, view)) {
// we must compute the real distinguished len of this sub-group
for document in group.iter() {
let entry = key_cache.entry(document.id);
let key = entry.or_insert_with(|| (self.function)(document.id, view).map(Rc::new));
match key.clone() {
Some(key) => buf_distinct.register(key),
None => buf_distinct.register_without_key(),
};
// the requested range end is reached: stop computing distinct
if buf_distinct.len() >= range.end { break }
}
documents_seen += group.len();
groups.push(group);
// if this sub-group does not overlap with the requested range
// we must update the distinct map and its start index
if buf_distinct.len() < range.start {
buf_distinct.transfert_to_internal();
distinct_raw_offset = documents_seen;
}
// we have sort enough documents if the last document sorted is after
// the end of the requested range, we can continue to the next criterion
if buf_distinct.len() >= range.end { continue 'criteria }
} }
} }
} }
let mut out_documents = Vec::with_capacity(limit); let mut out_documents = Vec::with_capacity(range.len());
let mut seen = DistinctMap::new(self.size); let mut seen = BufferedDistinctMap::new(&mut distinct_map);
for document in documents { for document in documents.into_iter().skip(distinct_raw_offset) {
let accepted = match (self.function)(document.id, view) { let key = key_cache.remove(&document.id).expect("BUG: cached key not found");
let accepted = match key {
Some(key) => seen.register(key), Some(key) => seen.register(key),
None => seen.register_without_key(), None => seen.register_without_key(),
}; };
if accepted { if accepted && seen.len() > range.start {
out_documents.push(document); out_documents.push(document);
if out_documents.len() == limit { break } if out_documents.len() == range.len() { break }
} }
} }